The Phylogeny of Anuran Larvae: A New Look
The Phylogeny of Anuran Larvae: A New Look
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无尾幼虫的系统发育：新面貌
作者：
Otto M. Sokol
喙蝌蚪是原始的，其中盘舌体(盘舌科和盘舌科)幼虫是最原始的。这些蝌蚪(和青蛙)与所有其他蝌蚪和青蛙形成对比，因为它们有单独的三叉神经节和面神经节，这是一种原始的性格状态。然而，与其他有喙的蝌蚪相比，下颌骨的特征使盘舌体幼虫无法进入祖先的位置。与共同祖先类型有关的分类群似乎已经灭绝。腭方悬吊带的变异可以把类幼虫分为原始和派生两个等级。然而，派生等级可能并不构成单一的系统线。小菱形幼虫可能是由小菱形幼虫进化而来的。鼻咽科和蝶科幼虫之间的相似之处是真实的；它们被归类为梨形幼虫。对笛蛙的化石记录表明，笛蛙的幼虫可以追溯到下侏罗世。据推测，这些形式融合了原始的孔状孔和神经节，就像活的管状动物一样。因此，具有这种派生特征状态的青蛙可能存在于下侏罗世。这将表明阿努拉的起源甚至更早于三叠纪，正如其他作者最近利用古生物学和动物地理证据所推测的那样。
Beaked tadpoles are primitive and among them discoglossoid (Ascaphidae and Discoglossidae) larvae are the most primitive. These tadpoles (and the frogs) contrast with all other tadpoles and frogs in having separate trigeminal and facial ganglia, a primitive character state. However, hyobranchial characters bar discoglossoid larvae from an ancestral position relative to other beaked (ranoid) tadpoles. Taxa referable to the common ancestral type appear to be extinct. Variations in the palatoquadrate suspensorium enable division of ranoid larvae into primitive and derived grades. However, the derived grade probably does not constitute a single phyletic line. Microhyloid (Microhylidae and Phrynomeridae) larvae probably evolved from derived ranoid larvae. The resemblance between rhinophrynid and pipid larvae is genuine; they are grouped as pipoid larvae. The fossil record of pipid frogs indicates that pipoid larvae date from the lower Jurassic. Presumably these forms had fused prootic foramina and ganglia as in living pipids. Thus, frogs with this derived character state probably existed during the lower Jurassic. This would indicate an even earlier Triassic origin for the Anura, as has recently been postulated by other authors employing paleontological and zoogeographical evidence.